This size is suitable for classic ?letter-box? style openings in fireplace surrounds. It will fit an opening that?s? 3? ? 5? deep (75 ? 125mm) by 10? ? 15? wide (250 ? 380mm). Make sure the Chimney Sheep is an inch or two bigger on each dimension than the chimney you are fitting it into. It comes with a 6? handle and 6? extension rod, giving 12? of reach altogether.